The insulating performance of a gas insulated switchgear is provided by accommodating a central conductor to which a high voltage is applied in a metallic grounded tank and filling an insulating gas in a space between the grounded tank and the central conductor. However, foreign matters (such as dust, fiber, or a conducting or semiconducting solid) may intrude into the grounded tank during manufacturing or an installation operation on site, which reduces the insulating performance. The intruded foreign matters are charged by an electric field generated at the time of energization and a receive electrostatic force in a direction to float up from an inner surface of the grounded tank. When the electrostatic force becomes larger than gravity acting on the foreign matters, the foreign matters float up and move toward the central conductor. The electric field concentrates around the foreign matters. Therefore, if the foreign matters approach the central conductor or adhere thereto, a high electric field is locally generated, which may reduce a voltage resistance performance of devices. Particularly in a case where the foreign matters are metallic and linear, the electric field concentrates intensively on ends of the foreign matters and thus the voltage resistance performance lowers greatly.
In order to handle this problem of metallic foreign matters, a conventional gas insulated switchgear described in Patent Literature 1, for example, has a non-linear resistance film having a non-linear resistance property on an inner surface of the tank to suppress partial discharge around metallic foreign matters to prevent charging of the metallic foreign matters and suppress floating-up of the metallic foreign matters.